"Å" is an old form of "på", used here in a deliberately archaic way. Today it is not normally used, except in some fixed phrases, notably "å andra sidan", where it on the other hand is completely normal. (Note that "å andra sidan" is normally not synonymous with "på andra sidan"! The first means "on the other hand", the later means "on the other side".)

The etymology of "på" is a bit interesting. The original form of this preposition was simply this "å" that you have noticed. It is related with the English "on". And just as in English, it was often used in the combination "uppå" ("upon"). But what happened was that this word started to be perceived as "upp-på" instead of "upp-å", and then people started to say "på" even without the preceding "upp". (Imagine, if you like, an alternative history form of the English language where "pon" is the regular preposition, and "on", to the extent it is used at all, sounds quaintly Victorian!)

No problem! I looked into your quotation a bit more, and it turned out that it originated from "Grönköpings Veckoblad", a long-standing humoristical publication where this kind of deliberate and exaggerated archaic language is de rigueur. It can be quite fun, but probably not the best example if you want to learn standard Swedish.